CAUDIN, Claude. Lettres, chiffres, figures comme langage formel de la logique. Acta Universitatis Lodziensis. Folia Philosophica. Ethica-Aesthetica-Practica, Poland, n. 7, p. 19–32, 1990. DOI: 10.18778/0208-6107.07.02. Disponível em: https://www.czasopisma.uni.lodz.pl/philosophica/article/view/17640. Acesso em: 10 aug. 2026.